1. Field of the Invention
The present invention relates to a mechanism for rotating a chuck top on which an object to be inspected is mounted and to a mount mechanism on which the object is mounted. More specifically, the present invention relates to a rotating mechanism and an object mount mechanism which reliably prevents the chuck top from being shifted in the xcex8 direction, and which reliably prevents an inspection probe needle from being shifted from the right inspection position on the object.
2. Discussion of the Background
A conventional probing apparatus for inspecting the electrical characteristics of integrated circuits (ICs) formed on a semiconductor wafer (hereinafter referred to as a wafer) is provided with a loading chamber 1 and a probing chamber 2, as shown in FIGS. 7 and 8. The loading chamber 1 is a chamber through which the wafer w is transported for pre-alignment, and the probing chamber 2 is a chamber in which the electrical characteristics of the IC formed on the wafer W transported from the loading chamber 1 are inspected. As shown in FIG. 8, a tweezers 3 and a subchuck 4, which jointly constitute a transport mechanism, are arranged in the loading chamber 1. The wafer w is transported by the trawzeers 3 and is pre-aligned on a sub-chuck 4 with reference to an orientation flat or a notch. Arranged inside the probing chamber 2 are a main chuck 5 on which the wafer w to be inspected is mounted, and an alignment mechanism 6 which is provided with a vertically-movable camera. Under the alignment mechanism 6, the main chuck 5 is moved in the X, Y, Z and xcex8 directions, so that the electrodes of the ICs formed on the wafer W are aligned with the probe needles 7A of a probe card 7. After the alignment, the electrical characteristics of the IC are inspected by a test head T in the state where the electrodes of the IC formed on the wafer of the main chuck 5 are kept in electric contact with the probe needles 7A. The main chuck 5 contains a temperature-adjusting mechanism. By this mechanism the temperature of the wafer W is kept in a relatively wide range (e.g., xe2x88x9250xc2x0 C. to +160xc2x0 C.), and a normal-temperature test, a low-temperature test, and a high-temperature test are conducted.
When the electrical characteristics of ICs formed on the wafer W are inspected, the wafer w is placed on the main chuck 5, and the temperature of this main chuck 5 is kept at a predetermined value by the temperature-adjusting mechanism. By the alignment mechanism 6, the electrodes of the ICs formed on the wafer W are aligned with the probe needles 7A. Thereafter, the main chuck 5 is raised in the Z direction until the electrode pads of the ICs formed on the wafer W are brought into electric contact with the probe needles 7A. In this state, the electrical characteristics of the ICs are inspected by the test head T. The probe card 7 is removably provided on a head plate 8, which is a top plate of the probing chamber 2.
As shown in FIG. 9, the main chuck 5 is provided with: a chuck top 5A, a support table 5B for supporting the chuck top 5A, and a ring-like bearing 5C arranged between the chuck top 5A and the support table 5B and having a cross roller. By means of a rotating mechanism shown in FIGS. 10 and 11, the chuck top SA is rotatable on the support table 5B, with the bearing 5C interposed. It is rotatable in the xcex8 direction normally and reversely. The rotating mechanism 8, 9, which is shown in FIGS. 10 and 11, is coupled to the chuck top 5A of the main chuck 5, and the chuck top 5A is rotated in the xcex8 direction normally and reversely.
The rotating mechanism 8 shown in FIG. 10 includes a motor 8A, a ball screw 8B coupled to the motor 8A, a nut 8C which is in engagement with the ball screw 8B, and a belt 8D which connects the nut 8C and the chuck top 5A in a crossed state. The rotating mechanism 8 rotates the chuck top 5A by means of the belt 8D in accordance with the movement of the nut 8C, and the chuck top 5A is rotated normally and reversely in the direction indicated by arrow xcex81.
The rotating mechanism shown in FIG. 11 includes a motor 9A, a ball screw 9B coupled to the motor 9A, a nut 9C which is in engagement with the ball screw 9B and coupled to the chuck top 5A, and a support member 9D for supporting the ball screw 9B. When the ball screw 9B is rotated, the nut 9C moves in the A directions. In accordance with this movement of the nut 9C, the chuck top 5A is rotated normally and reversely in the direction indicated by arrow xcex81.
In accordance with the development of ultrafine integrated circuits formed on semiconductor wafer, electrode pads are arranged at narrower pitches, and the number of ICs measured at a time is increasingly large. Under the circumstances, the number of probe needles 7A used in the measurement is increasingly large. Due to the use of a large number of probe needles 7A, the total pressure exerted on the semiconductor wafer through the probe needles 7A is very high since the pressure exerted on an electrode pad of the semiconductor wafer by one probe remains the same. In particular, when an ICs formed on the periphery of a wafer W is inspected, a needle pressure as large as several kg is applied to the chuck top 5A as an eccentric load, as indicated by the arrow in FIG. 9. In general, the outer diameter of the ring-like bearing 5C is very small in comparison with the outer diameter of the chuck top 5A or support table 5C, and there is a gap in the areas outward of the ring-like bearing 5C. The eccentric load exerted on the chuck top 5A elastically deforms the bearing though slightly, and the chuck top 5A slants, as indicated exaggeratedly with the one-dot-dash line in FIG. 5A. As a result, the probe needles 7A are shifted from the desirable alignment positions, and the reliability of the inspection is significantly lowered.
Where the wafer size is large in diameter, the distance between the center of the main chuck 5 and the point of action is long in comparison with the corresponding distance of the prior art, thus resulting in a more marked slant of the main chuck 5. In addition, the pressures applied from the probe needles 7A may significantly differ, and some of the probe needles 7A may not be in contact with the electrode pads of the ICs formed on the wafer W. Thus, the reliability of the inspection is markedly degraded.
The rotating mechanism 8 shown in FIG. 10 is coupled to the chuck top 5A by means of the belt 8D. With this structure, the chuck top 5A is not very rigid in the xcex81 direction. When the main chuck 5 is overdriven, the eccentric load which is applied to the chuck top 5A when the wafer and the probe needles are brought into contact rotates the chuck top in the xcex8 direction, resulting in a positional shift. By this positional shift, the reliability of the inspection is adversely affected.
In the rotating mechanism 9 shown in FIG. 11, the ball screw 9B swings in the xcex82 direction with the support member 9D as a center. With this structure, the rotating mechanism 9 is not very rigid in the xcex82 direction, and extra space is needed for the ball screw 9B to swing. At the present time, more and more ultrafine chips are developed, and more and more large-diameter wafers are developed. Under the circumstances, there is an urgent demand for a solution to the above problems.
To solve the problems described above, the present invention is intended to provide a mechanism for mounting an object to be inspected, which enables the main chuck to be kept in the horizontal state at all times, even if an eccentric load is exerted in the neighborhood of the outer periphery of the chuck top, thereby enhancing the reliability of the inspection.
The present invention is also intended to provide a rotating mechanism and an object mount mechanism which provide an increased rigidity in the xcex8 direction when the probe needles are brought into contact and which reliably prevent the chuck top from being rotated in the xcex8 direction.
In accordance with the first aspect of the present invention, there is provided a rotating mechanism comprising:
a movable body;
a linearly driving mechanism including a driving shaft along which the movable body is linearly moved on a side of the chuck top by a driving force of a motor;
a guide mechanism including a guide rail for linearly guiding the movable body; and
a coupling mechanism for coupling the movable body and the chuck top together and converting a linear motion of the movable body into a rotating motion of the chuck top, the rotating mechanism rotating the chuck top in normal and reverse directions, the chuck top being rotatably supported and holding an object to be inspected.
In the rotating mechanism, it is preferable that the driving shaft of the linearly driving mechanism be a ball screw, the movable body be provided with a through hole having a groove that is engageable with the ball screw, and the coupling mechanism be a link device connected to the chuck top and the movable body at respective ends.
In the rotating mechanism, it is preferable that the driving shaft of the linearly driving mechanism be a ball screw, the movable body be provided with a through hole having a groove that is engageable with the ball screw, and the coupling mechanism include a splined shaft having one end connected to the chuck top, a link device having one end connected to the other end of the splined shaft, and a support shaft coupled to the other end of the link device and standing upright on the movable body.
In the rotating mechanism, it is preferable that the guide rail be an LM guide that is engageable with the lower portion of the movable body.
In accordance with the second aspect of the present invention, there is provided a rotating mechanism comprising: a movable body; a linearly driving mechanism for linearly moving the movable body on a side of the chuck top; a guide mechanism for linearly guiding the movable body; and coupling means for coupling the movable body and the chuck top together and converting a linear motion of the movable body into a rotating motion of the chuck top, the rotating mechanism rotating the chuck top in normal and reverse directions, the chuck top being rotatably supported and holding an object to be inspected.
In accordance with the third aspect of the present invention, there is provided a mount mechanism for mounting an object to be inspected, comprising:
a chuck top on which the object is mounted;
a support table for supporting the chuck top to be rotatable in normal and reverse directions, the support table being provided with a vacuum suction mechanism having a vacuum exhaust passage which sucks and fixes the chuck top on the support table by a vacuum force;
a rotating mechanism for rotating the chuck top on the support table in normal and reverse directions; and
a lift guide mechanism for guiding a vertical movement of the chuck top on the support table.
In the mount mechanism, it is preferable that the support table be provided with a lift mechanism that has a gas supply/exhaust passage. This passage is for enabling the chuck top to float away from the support table by utilization of a gas pressure, and for enabling the chuck top to land on the support table by releasing the gas pressure.
In the mount mechanism, it is also preferable that the vacuum suction mechanism include: a projected wall section arranged on the upper surface of the support table, being in contact with the lower surface of the chuck top, and defining a sealed space with reference to the upper surface of the support table and the lower surface of the chuck top; and a vacuum exhaust passage which is open in the upper surface of the support table at a position inside of the projected wall section, and that the lift mechanism include a projection formed on the upper surface of the support table, and an air supply passage which is open in the projection.
In the mount mechanism, it is preferable that a projection be provided in the neighborhood of the outer circumstance of the upper surface of the support table. The chuck top is landed on the projection when it is attracted by vacuum suction.
In the mount mechanism, it is preferable that at least one of the vacuum suction mechanism and lift mechanism be provided as the projection.
In the mount mechanism, it is preferable that the vacuum suction mechanism and the lift mechanism be arranged at equal intervals with respect to the circumferential direction of the support table.
In the mount mechanism, it is preferable that the lift guide mechanism include a shaft supported by one of the chuck top and the support table, and an engagement member secured to the other one of the chuck top and support table and being in engagement with the shaft in such a manner that the shaft is vertically movable.
In the mount mechanism, it is preferable that the lift guide mechanism include a splined shaft supported by one of the chuck top and the support table, and an engagement member secured to the other one of the chuck top and support table and being movable in engagement with the splined shaft.
In the mount mechanism, it is preferable that the rotating mechanism include: a movable body; a linearly driving mechanism for linearly moving the movable body on a side of the chuck top; a guide mechanism including a guide rail for linearly guiding the movable body; and coupling means for coupling the movable body and the chuck top together and converting a linear motion of the movable body into a rotating motion of the chuck top.
In the mount mechanism, it is preferable that the driving shaft of the rotating mechanism be a ball screw, the movable body of the rotating mechanism be provided with a through hole having a groove that is engageable with the ball screw, and the coupling mechanism of the rotating mechanism be a link device coupled to the chuck top and the movable body at respective ends.
In the mount mechanism, it is preferable that the driving shaft of the rotating mechanism be a ball screw, the movable body of the rotating mechanism be provided with a through hole having a groove that is engageable with the ball screw, and the coupling mechanism include a splined shaft having one end connected to the chuck top, a link device having one end connected to the other end of the splined shaft, and a support shaft coupled to the other end of the link device and standing upright on the movable body.
In the mount mechanism, it is preferable that the guide rail of the rotating mechanism be an LM guide that is engageable with the lower portion of the movable body.
In accordance with the fourth aspect of the present invention, there is provided a mount mechanism for mounting an object to be inspected, comprising:
mount means for mounting an object to be inspected;
support means for supporting the mount means to be rotatable in normal and reverse directions, the support means including a vacuum suction mechanism which sucks and fixes the mount means on the support means, and a lift mechanism for lifting the mount means away from the support means in a floating state;
a rotating mechanism for rotating the mount means on the support table in normal and reverse directions; and
a lift guide mechanism for guiding a vertical movement of the chuck top on the support means.
In accordance with the fifth aspect of the present invention, there is provided an inspection apparatus for inspecting an integrated circuit formed on a semiconductor wafer, comprising:
a chuck top on which the semiconductor wafer is mounted;
a support table for supporting the chuck top to be rotatable in normal and reverse directions, the support table being provided with a vacuum suction mechanism which sucks and fixes the chuck top on the support table by a vacuum force, and a lift mechanism for lifting the chuck top away from the support table in a floating state, the vacuum suction mechanism including a projected wall section arranged on the upper surface of the support table, being in contact with the lower surface of the chuck top, and defining a sealed space with reference to the upper surface of the support table and the lower surface of the chuck top, and a vacuum exhaust passage which is open in the upper surface of the support table at a position inside of the projected wall section, the lift mechanism including a projection formed on the upper surface of the support table, and an air supply passage which is open in the projection; and
a rotating mechanism for rotating the chuck top on the support table in normal and reverse directions, the rotating mechanism being provided with: a linearly driving mechanism including a ball screw which is rotated by a driving force of a motor on a side of the chuck top; a movable body being provided with a through hole having a groove that is engageable with the ball screw; a guide rail for linearly guiding the movable body; and a coupling mechanism including a splined shaft having one end connected to the chuck top, a link device having one end connected to the other end of the splined shaft, and a support shaft coupled to the other end of the link device and standing upright on the movable body.